Neanderthal gene can confer protection against severe COVID-19, finds study Some of the genes in the human genome appear to confer a protective effect against severe coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A new paper published online in the journal PNAS describes genes involved in innate immunity that have undergone variations between different human subgroups. Infectious disease and genetic changes Infectious diseases vary in prevalence with environmental conditions, which vary dramatically in different parts of the world. These act as selective factors on gene variants, such as the toll-like receptor gene variants that reduce the susceptibility to some bacterial infections and allergies.